This book is about selectively toxic agents. That is to say, it is about
those substances that affect certain cells without harming others, even
when they are close neighbours. Toxicity need not be fatal. It can be
made easily reversible, as is the case with general anaesthetics.
Selective toxicity covers an immense field: most of the drugs used for
treating illness in man and his economic animals, as well as all of the
fungicides, insecticides, and weed killers that are used in agriculture.
Essentially, this book is a discussion of the physical and chemical
means which contribute to selectivity, and this is the basis of
molecular pharmacology. _Selective Toxicity began as a course of
lectures that Professor F. G. Young encouraged me to give in University
College London, in 1948 and again in 1949. The first edition appeared in
1951, as a very small book because little was then known about the
factors that provide selectivity. Since those early days, the subject
has undergone tremendous development. At first, industry was un-
receptive to the word 'toxicity', however qualified! Yet the market was
being supplied with biologically powerful substances of which several
had the potential to cause harm. This aspect was brought to light by two
events of the early 1960s. The first of these was the discovery that a
sedative, thalidomide, administered to expectant mothers, after what was
then considered to be adequate testing, had caused permanent deformities
in about 10000 children.